1. Field of the Invention
The present invention relates to an auto-tensioner for belt systems such as a timing-belt device and a V-shaped belt device, particularly, a belt system which controlls the belt tension by using an idler.
2. Description of the Prior Art
FIG. 2 shows one example of conventional auto-tensioner devices, which is disclosed in the Japanese Laid-open Patent Bulletin Jitsu-ko-sho 60-52458. In this auto-tensioner device, bracket 1 fixed to the vehicle body side supports auto-tensioner 2 by screw 3 and lock nut 4. Pulley holder 5 is pivotally fixed to bracket 1, and piston 6 is contacted with pulley holder 5. Idler pulley 7, which is rotatably held by pulley holder 5, is contacted with and pushed to the unfastened side of belt 8. Pulley holder 5 is equipped with spring 9 which is fixed to a fast member at its one end, thereby pulley holder being biased.
However, in the conventional auto-tensioner having such construction as mentioned in FIG. 2, the position of the tensioner has to be adjusted by screw 3 and lock nut 4 for setting tension, as tensioner 2 is fixed to a fast bracket 1. In this adjustment, the protruding degree of piston 6 has to be adjusted while rotating belt 8, by starting an engine. This makes the adjustment of tensioner to be troublesome especially in a mass-production line.